Yangtze floods recorded on Mt. Mufu and Swallow Cliff in Nanjing, China

Abstract

The Yangtze drainage basin is the most densely populated and prosperous area of China; however, it is frequently threatened by floods. The Holocene flood lines of the Yangtze River have been preserved on Mt. Mufu and Swallow Cliff in north-eastern Nanjing, and they are characterised by the presence of particular colour tones and the horizontal arrangement of erosional pits and holes. Four major paleo-flood lines at altitudes of 8.51, 9.43, 10.47, and 12.84 m were identified via a field survey along the river bank. Historical literature and instrumental flood records extend the paleo-flood stage to the contemporary era and indicate that the highest flood line of 12.84 m represents a maximum limit for future floods. Besides, the flood line at 10.47 m can be regarded as a foreseeable extreme flood risk level with a recurrence interval of 100–200 years, especially considering the current circumstances of rising sea levels and decreasing flood storage capacities caused by human activities.